If I wait until the gas light comes on I pump about 13.5 gallons which comes out to about 275 miles on average. The most miles I have gone on a tank was around 350 and the least was around 250.

The most important number is the mpg b/c that number can be compared to any car regardless of tank size.

No, what this thread is missing is whether you have A/C on or not -- that's critical information. I get 300 miles per tank with A/C off, and 270-275 (as low as 250) miles per tank with it on -- I use the same type of gas every time (Shell Vpower 91) and drive the exact same distance every day (21 mile commute) at similar times, and that difference always shows up between summer (A/C on all the time) and winter (AC off).

No, what this thread is missing is whether you have A/C on or not -- that's critical information. I get 300 miles per tank with A/C off, and 270-275 (as low as 250) miles per tank with it on -- I use the same type of gas every time (Shell Vpower 91) and drive the exact same distance every day (21 mile commute) at similar times, and that difference always shows up between summer (A/C on all the time) and winter (AC off).

I don't think I have ever used a full tank of gas with a/c on the whole time. I don't use the a/c very often, but obviously I use it more in the summer. If the a/c had a large impact in my mileage I would see a drop during the summer months. I will have to wait and see...this will be my first summer with this car.

I think the amount throttle used and driving conditions would impact mileage far more than a/c. When I drove up to lake tahoe I got 26 mpg with no traffic and hardly ever boosting. Then when I went to a car control clinic and a few "spirited" drives my mileage plunged to 18 mpg. Whats the main difference between these two types of drives...in a word...BOOST!!!

... I know I get better mileage when I go closer to the speed limit (65) on the freeway- but does anyone know what the most efficient speed is? And would certain mods increase this speed (or overall mileage)?

Recently I've been getting 30.5-31.5 in my RS. I got a job as a courier, and it's 90% freeway miles. What amazes me is that I can get that much with 5-700 pounds of stuff filling the trunk and backseat!

What's your average speed on the freeway? I want to see those numbers if at all possible.

One more question... Would finishing off my exhaust by replacing the cat-section with something high-flow be good or bad for mileage?

What's your average speed on the freeway? I want to see those numbers if at all possible.

Right at 65. I'm cheating though; I'm going up and down the mountains here, and I coast whenever I can keep it above 65 off the throttle. Probably 25-30 miles a day at idle, heh. So I don't think you can expect more than 28-29 mpg normally.

Quote:

Originally Posted by scoobsport98

One more question... Would finishing off my exhaust by replacing the cat-section with something high-flow be good or bad for mileage?

Probably good... but not enough to make up for the money you spent on it.

I think the amount throttle used and driving conditions would impact mileage far more than a/c. When I drove up to lake tahoe I got 26 mpg with no traffic and hardly ever boosting. Then when I went to a car control clinic and a few "spirited" drives my mileage plunged to 18 mpg. Whats the main difference between these two types of drives...in a word...BOOST!!!

As I said, I have controlled for factors such as different driving styles, etc. and without changing my driving habits or styles AT ALL, the a/c makes a 30+ miles-per-tank difference, 100% of the time.

However, (and yes, I realize how useless one data point is), I took a trip a few months back which included about 220 miles of driving on soft dirt and sand, and I spent almost the entire time under boost -- essentially making a desert back-road into a rally course, with my brother as the co-driver. I drove the CRAP out of the car; near the end of the run I stopped and looked under the car and saw that the turbo was glowing red.

I've managed to get 24 mpg by being as light on the throttle as I possible could. Cruising at constant speed (75-80mph) on the highway yields 26, maybe 27. Over the winter, if it's cold, the fuel economy goes down noticeably. Also, I've been keeping the tire pressure in my Sumitomo HTR+ tires higher than before in an effort to improve economy. I run 38psi front and 36 rear (+/- a couple psi)

1998 Subaru Legacy 2.5 gt sedan
27 MPG (best ive ever got)
2.25 a gallon, some small place in my town sells for about 1.95 a gallon so i go there as much as possible
Regular Fuel
mostly driving around town

never got the 24 mpg on the highway. even when i took a trip a month after getting it (and broken in CORRECTLY) with a 1400 mil round trip where 95% of the miles was spent on I-5 (from san fran area to portland).

now, and i still maintain records for EVERY fill up, i get 18-19 normal dailiy driving. 22-23 highway...